1. Field of the Invention
The present invention relates to an anti-inflammatory factor, processes for its production in substantially pure or highly pure form, and a method for its use in the treatment of inflammation.
2. Description of the Background Art
Inflammation, as defined in Dorland's Medical Dictionary, is "a localized protective response elicited by injury or destruction of tissues which serves to destroy, dilute or wall off both the injurious agent and the injured tissue." It is characterized by fenestration of the microvasculature, leakages of the elements of blood into the interstitial spaces, and migration of leukocytes into the inflamed tissue. On a macroscopic level, this is usually accompanied by the familiar clinical signs of erythema, edema, tenderness (hyperalgesia), and pain. During this complex response, chemical mediators such as histamine, 5-hydroxytryptamine, various chemotactic factors, bradykinin, leukotrienes, and prostaglandins are liberated locally. Phagocytic cells migrate into the area, and cellular lysosomal membranes may be ruptured, releasing lytic enzymes. All of these events may contribute to the inflammatory response.
Inflammation in patients with rheumatoid arthritis probably involves the combination of an antigen (gamma globulin) with an antibody (rheumatoid factor) and complement causing the local release of chemotactic factors that attract leukocytes. The leukocytes phagocytose the complexes of antigen-antibody and complement and also release the many enzymes contained in their lysosomes. These lysosomal enzymes then cause injury to cartilage and other tissues, and this furthers the degree of inflammation. Cell-mediated immune reactions may also be involved. Prostaglandins are also released during this process.
Prostaglandins, which are likely to be generated in inflammation, cause erythema and increase local blood flow. Two important vascular effects of prostaglandins are not generally shared by other mediators of inflammation--a long-lasting vasodilator action and a capacity to counteract the vasoconstrictor effects of substances such as norepinephrine and angiotensin.
A number of mediators of inflammation increase vascular permeability (leakage) in the post-capillary and collecting venules. In addition, migration of leukocytes into an inflamed area is an important aspect of the inflammatory process.
The Arthus reaction is an inflammatory response brought about by the formation of immune complexes at subcutaneous sites where an antigen complexes with antibody to that antigen. Neutrophils characteristically attach to the Fc portion of the immunoglobulin complex that forms at the subcutaneous injection site where they release digestive enzymes, causing visible acute inflammation. Thus the reaction is primarily neutrophil-mediated and agents that effect the development of the reaction do so via an effect on these cells.
There are several pathways whereby an agent might interfere with neutrophil migration from the blood vessels to an inflammatory site. One likely pathway is the inhibition of margination, the reversible "sticking" of inflammatory cells to the endothelial cell lining of the blood vessel wall. In the normal state about 50% of neutrophils are reversibly adhered, but during an acute inflammatory response, adhesion becomes much stronger and is a key step in the process of neutrophil migration. While prostaglandins are unlikely to be directly involved in the chemotactic response, another product of the metabolism of arachidonic acid, leukotriene, is a very potent chemotactic substance.
The anti-inflammatory response is any response characterized by inflammation as defined above. It is well known to those skilled in the medical arts that the inflammatory response causes much of the physical discomfort, i.e., pain and loss of function, that has come to be associated with different diseases and injuries. Accordingly, it is a common medical practice to administer pharmacological agents which have the effect of neutralizing the inflammatory response. Agents having these properties are classified as anti-inflammatory drugs. Anti-inflammatory drugs are used for the treatment of a wide spectrum of disorders, and the same drugs are often used to treat different diseases. Treatment with anti-inflammatory drugs is not for the disease, but most often for the symptom, i.e., inflammation.
The anti-inflammatory, analgesic, and anti-pyretic drugs are a heterogeneous group of compounds, often chemically unrelated, which nevertheless share certain therapeutic actions and side-effects. Corticosteroids represent the most widely used class of compounds for the treatment of the anti-inflammatory response. Proteolytic enzymes represent another class of compounds which are thought to have anti-inflammatory effects. Hormones which directly or indirectly cause the adrenal cortex to produce and secrete steroids represent another class of anti-inflammatory compounds. A number of non-hormonal anti-inflammatory agents have been described. Among these, the most widely used are the salicylates. Acetylsalicylic acid, or aspirin, is the most widely prescribed analgesic-antipyretic and anti-inflammatory agent. Examples of steroidal and non-steroidal anti-inflammatory agents are listed in the Physician's Desk Reference, 1987 (see pp. 207 and 208 for an index of such preparations).
The natural and synthetic corticosteroid preparations cause a number of severe side effects, including elevation of blood pressure, salt and water retention, and increased potassium and calcium excretion. Moreover, corticosteroids may mask the signs of infection and enhance dissemination of infectious microorganisms. These hormones are not considered safe for use in pregnant women, and long-term corticosteroid treatment has been associated with gastric hyperactivity and/or peptic ulcers. Treatment with these compounds may also aggravate diabetes mellitus, requiring higher doses of insulin, and may produce psychotic disorders. Hormonal anti-inflammatory agents which indirectly increase the production of endogenous corticosteroids have the same potential for adverse side-effects.
The non-hormonal anti-inflammatory agents are synthetic biochemical compounds which can be toxic at high doses with a wide spectrum of undesirable side-effects. For example, salicylates contribute to the serious acid-base balance disturbances that characterize poisoning by this class of compounds. Salicylates stimulate respiration directly and indirectly. Toxic doses of salicylates cause central respiratory paralysis as well as circulatory collapse secondary to vasomotor depression. The ingestion of salicylate may result in epigastric distress, nausea, and vomiting. Salicylate-induced gastric bleeding is well known. Salicylates can produce hepatic injury, and lead to a prolongation of clotting time. Therefore, aspirin should be avoided in patients with severe hepatic damage, hypoprothrombinemia, vitamin K deficiency, or hemophilia, because the inhibition of platelet hemostasis by salicylates can result in hemorrhage. Salicylate intoxication is common, and over 10,000 cases of serious salicylate intoxication are seen in the United States every year, some of them being fatal, and many occurring in children. See Goodman and Gilman's The Pharmacological Basis of Therapeutics, 7th Ed., 1985. Accordingly, in spite of the large number of anti-inflammatory agents that are currently available, there still exists a need for a safe, effective anti-inflammatory product which is free of side-effects and adverse reactions.
If a natural food product, such as one derived from milk, for example, could be obtained having anti-inflammatory effects, it would be an easily administrable, readily available, safe therapeutic composition.
It has been known in the prior art to produce milks having a variety of therapeutic effects. Beck, for example, has disclosed a milk containing antibody to Streptococcus mutans that has dental caries inhibiting effect (U.S. Pat. No. 4,324,782). The milk is obtained by immunizing a cow with S. mutans antigen in two stages and obtaining the therapeutic milk therefrom.
Stolle et al. have disclosed a method for treating vascular disorders or pulmonary disorders associated with smoking in an animal which comprises administering to the animal milk collected from a cow being maintained in a hyperimmune state (U.S. Pat. No.4,636,384). Beck has disclosed a method for treating inflammation in an animal which comprises administering to the animal an anti-inflammatory effective amount of milk collected from a cow maintained in an anti-inflammatory factor producing state (U.S. Pat. No. 4,284,623). Heinbach, U.S. Pat. No. 3,128,230, has described milk containing globulins of alpha, beta, and gamma components by inoculating a cow with antigenic mixtures. Peterson et al. U.S. Pat. No. 3,376,198), Holm (U.S. application (published) Ser. No. 628,987), Tunnah et al. (British Patent No. 1,211,876) and Biokema S. A. (British Patent 1,442,283) have also described antibody-containing milks.
None of the aforementioned references, however, disclose the identity of the component or components of therapeutic milks which produce the desired therapeutic effects. For example, in Beck, U.S. Pat. No. 4,284,623, the milk products used as a therapeutic means consist of either fluid whole milk, fluid fat-free whey, or whole milk powders. Although each of these milk products has anti-inflammatory properties, the factor or factors that actually provide the therapeutic benefits have not yet been isolated or identified or purified to homogeneity.
A particular difficulty in obtaining highly purified preparations of milk anti-inflammatory factor(s) (MAIF) is the inability to remove tightly bound salts from the MAIF by currently used purification procedures. One of the problems that this invention addresses, inter alia, is the large scale preparation of MAIF including the elimination of tightly bound salts from the MAIF preparation, thereby resulting in highly purified MAIF. Further, problems have previously arisen in obtaining highly pure, preparative scale preparations of MAIF when beginning with large volumes of starting materials (e.g. 90 liters of skim milk). The invention provides solutions to these problems.